<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title>Page Title</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>

</head>

<body>
    <div id="box">
        <input v-model="message" placeholder="edit me">
        <p>Message is: {{ message }}</p>

        <hr>
        <span>Multiline message is:</span>
        <p style="white-space: pre-line;">{{ message }}</p>
        <br>
        <textarea v-model="message" placeholder="add multiple lines"></textarea>

    </div>
</body>
<script>
    var vm = new Vue({
        el: "#box",
        data: {
            message: ''
        }
    })
</script>

</html>